Continuous carburizing furnace

Abstract

A furnace includes a carburizing zone in which carburizing processing is performed upon workpieces loaded upon trays during the conveyance, and a plurality of regions which are arranged at the upstream side of the carburizing zone. Along with a tray upon which workpieces are loaded being mounted upon each one of the plurality of pallets, these pallets are movable along a linear conveyance direction, with the number of pallets being the same as the number of regions. The pusher device pushes the trays along the direction of conveyance. And the pusher-puller device, along with pushing the plurality of pallets all together forward along the direction of conveyance, also pulls one of the plurality of pallets backward into each of the plurality of regions.

1. A continuous carburizing furnace, comprising:
 a furnace which comprises a carburizing zone in which carburizing processing is performed upon workpieces loaded upon trays during the conveyance of said trays along a direction of conveyance, and a plurality of regions which are arranged successively along said direction of conveyance at the upstream side of said carburizing zone;
 a plurality of pallets, the same in number as said plurality of regions, upon each of which one said tray is mounted, and which are movable to and fro along said direction of conveyance within a single plane; 
 a pusher device which pushes said trays along said direction of conveyance; and 
 
 a pusher-puller device which, along with pushing said plurality of pallets all together forward along said direction of conveyance, also pulls each of said plurality of pallets backward into each of said plurality of regions. 
 
     
     
       2. A continuous carburizing furnace according to  claim 1 , further comprising a plurality of intermediate doors which selectively open or close between each adjoining pair of said plurality of regions, and between the one of said plurality of regions most on the downstream side and said carburizing zone respectively. 
     
     
       3. A continuous carburizing furnace according to  claim 2 , wherein: said plurality of regions are arranged in this order along said direction of conveyance: an introduction chamber in which the trays wait before the start of conveyance; a purge chamber in which the trays are isolated from the external air; and a heating chamber in which these workpieces are heated up to a preheating temperature which is lower than the carburizing temperature during said carburizing processing; and
 said plurality of pallets consists of three pallets upon which are mounted three trays which are to be respectively disposed in said introduction chamber, said purge chamber, and said heating chamber. 
 
     
     
       4. A continuous carburizing furnace according to  claim 1 , wherein said pusher-puller device comprises a projecting member which, when said plurality of pallets are moved forwards, contacts against that pallet among said plurality of pallets which is most to the upstream side along said direction of conveyance towards the downstream side in said direction of conveyance, and a hook mechanism which, as said plurality of pallets are moved backwards, sequentially changes over, at each of the boundary positions between said plurality of regions, its engagement to the next pallet among said plurality of pallets which is positioned more to the upstream side in said direction of conveyance. 
     
     
       5. A continuous carburizing furnace according to  claim 1 , wherein said pusher-puller device is built as a link chain.